Durable omniphobic nanocoating and method of making the same

Abstract

This invention belongs to the field of coatings, and particularly relates to a durable superhydrophobic nano-coating and its preparation method. The raw material composition of the durable superhydrophobic nano-coating includes, by weight: 5-50 parts ethylenediaminetetraacetic acid, 0.1-50 parts hydrophilic nano-silica dispersion, 10-50 parts anhydrous ethanol, 10-50 parts monohydric alcohol, 0.1-20 parts perfluoroorganosilane, and 0.1-5 parts catalyst. This invention solves the problems of cumbersome preparation processes, long reaction times, and harsh curing conditions in existing superhydrophobic coatings, achieving excellent superhydrophobic effects on substrates such as fabrics through simple spraying.

Description

Technical Field

[0001] This invention belongs to the field of coatings, and particularly relates to a durable superhydrophobic nano-coating and its preparation method. Background Technology

[0002] Superhydrophobic refers to a surface where the contact angle with both water and oil is greater than 150° and the roll-off angle for both is less than 10°. Products with durable superhydrophobic nano-coatings not only avoid damage from water immersion but also have a longer lifespan. With the development of waterproofing technology, the market has placed higher demands on superhydrophobic products that are both oleophobic and hydrophobic. Currently, durable superhydrophobic nano-coatings have extremely high application value in waterproofing, moisture resistance, self-cleaning, stain resistance, and anti-icing due to their unique surface properties.

[0003] To achieve superhydrophobic and superoleophobic properties, existing technologies typically involve liquid-phase deposition on the substrate under normal pressure, prompting the film-forming material to undergo a grafting reaction on the substrate surface and grow a superhydrophobic and superoleophobic coating. However, this approach is limited by the shape and size of the substrate. Currently reported superhydrophobic and superoleophobic coatings used on substrates such as fabrics, glass, and metals are based on the principle of grafting fluorosilanes onto nanoparticles after hydrolysis, giving the nanoparticles extremely low surface energy and thus exhibiting superhydrophobic and superoleophobic properties. In recent years, due to the diversification of consumer demands, applying superhydrophobic and superoleophobic coatings to clothing, footwear, and other products has become one of the main ways to add additional functions to textile products. However, most existing superhydrophobic and superoleophobic coatings suffer from problems such as cumbersome preparation processes, long reaction times, and harsh curing conditions, failing to meet the demands for high efficiency, convenience, short processing time, and stability in actual production.

[0004] CN115323352A discloses a method for preparing a sprayable superhydrophobic coating with a micro-nano composite structure. This method employs a vapor deposition apparatus, which includes a vapor deposition chamber and storage chambers located on either side of it. The vapor deposition chamber of the vapor deposition chamber is connected to the storage chambers of the storage chambers via pipelines, each equipped with a valve. A stirring device is installed in the vapor deposition chamber, and a pressure monitoring device is mounted on the vapor deposition chamber. Therefore, CN115323352A requires the use of a vapor deposition apparatus with a complex structure.

[0005] CN115506160A discloses a method for preparing a water-based dual-repellent coating, comprising the following steps: uniformly dispersing a surfactant in water, adding a long-chain fluorocarbon substance, and stirring at room temperature until homogeneous to obtain liquid A; adding ammonia water to liquid A, then adding substance D, and stirring at room temperature for 12–96 hours to obtain liquid B; adding a water-soluble polyurethane binder to liquid B and stirring until homogeneous to obtain liquid C, wherein substance D is a water-soluble silicon oxide compound or mixture E, mixture E is a mixture of water-soluble silicon oxide compound and oxide nanoparticles, and the surfactant is an aqueous solution of allyl amine; adding a silane coupling agent to diluted or undiluted liquid C and stirring until homogeneous to obtain the water-based dual-repellent coating. However, CN115506160A requires a lengthy preparation process.

[0006] CN105349036A discloses a water-based transparent superhydrophobic nanocoating. The method involves reacting a hydrophilic silica nanoparticle ethanol solution with tetraethyl orthosilicate or silicon tetrachloride, then adding a silane coupling agent for coupling, followed by reaction with a fluorosilane to obtain an oil-based nanocoating. The oil-based nanocoating is then uniformly mixed with a fluorocarbon resin to obtain an organic-inorganic hybrid coating. Rotary evaporation and concentration yield a high-solids-content oil-based nanocoating concentrate. Finally, water is added for ultrasonic dispersion and dilution to a predetermined concentration to obtain the water-based transparent superhydrophobic nanocoating. The preparation of the superhydrophobic nanocoating using CN105349036A is complex and difficult to apply to industrial production.

[0007] CN109647680A discloses a method for preparing a nano-ZnO-GO / waterborne polyurethane superhydrophobic coating using a spraying method, comprising the following steps: dispersing nano-ZnO in anhydrous ethanol, adding perfluorooctyltrichlorosilane modifier and water, and magnetically stirring to form solution A; dispersing graphene oxide in anhydrous ethanol, and ultrasonically treating to form a uniformly dispersed suspension B; mixing solution A and suspension B to obtain solution C, and magnetically stirring under a 60°C water bath; washing with deionized water and anhydrous ethanol, filtering, and vacuum drying the product to obtain the nano-ZnO-GO composite, which is then ground for later use; weighing waterborne polyurethane components A and B, stirring evenly, aging at room temperature, and then spraying onto the treated aluminum substrate surface, followed by curing at room temperature; preparing a solution of the nano-ZnO-GO composite using dichloromethane or acetone as the solvent; uniformly spraying the nano-ZnO-GO composite solution onto the waterborne polyurethane coating; allowing the constructed coating to air dry at room temperature, and then vacuum drying. The thickness of the waterborne polyurethane coating in CN109647680A can easily affect its embedding and bonding with the ZnO-GO composite layer, and its high curing temperature makes it unsuitable for preparing superhydrophobic coatings on the surfaces of finished products such as garments and shoes. Summary of the Invention

[0008] In view of the above, in order to solve the problems of complicated preparation process, long reaction time and harsh curing conditions of existing superhydrophobic coatings, this invention proposes a durable superhydrophobic nano-coating and its preparation method, which can achieve excellent superhydrophobic effect on the surface of substrates such as fabrics through simple spraying.

[0009] In a first aspect, the present invention provides a durable superhydrophobic nano-coating. The raw material composition of the durable superhydrophobic nano-coating includes, by weight, 5-50 parts of ethylenediaminetetraacetic acid, 0.1-50 parts of hydrophilic nano-silica dispersion, 10-50 parts of anhydrous ethanol, 10-50 parts of monohydric alcohol, 0.1-20 parts of perfluorinated organosilane, and 0.1-5 parts of catalyst.

[0010] Preferably, the raw material composition of the durable superhydrophobic nano-coating includes: by weight, 14-18 parts of ethylenediaminetetraacetic acid, 5-11 parts of hydrophilic nano-silica dispersion, 20-26 parts of anhydrous ethanol, 47-50 parts of monohydric alcohol, 2-6 parts of perfluoroorganosilane, and 0.1-1 parts of catalyst.

[0011] Preferably, the perfluoroorganosilane is a long-chain perfluoroorganosilane. More preferably, the long-chain perfluoroorganosilane has ≥13 fluorine atoms.

[0012] Preferably, the perfluoroorganosilanes are selected from one or a mixture of several of perfluorodecyltriethoxysilane, perfluorodecyltrimethoxysilane, perfluorohexadecyltriethoxysilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctylsilane.

[0013] Preferably, the silica concentration of the hydrophilic nano-silica dispersion is 10-30 wt%.

[0014] Preferably, the solvent of the hydrophilic nano-silica dispersion is selected from one or more mixtures of methanol, ethanol, isopropanol, butanol, sec-butanol, isobutanol, methyl ethyl ketone, and water.

[0015] Preferably, the mass ratio of the nano-silica to the perfluoroorganosilane is between (0.1 to 4): 1, more preferably between (0.3 to 2): 1, and even more preferably between (0.3 to 1): 1.

[0016] Preferably, the catalyst is selected from one or more of glacial acetic acid, hydrochloric acid, sulfuric acid, nitrous acid, phosphoric acid, formic acid, oxalic acid, propionic acid, and maleic acid.

[0017] Preferably, the monohydric alcohol is selected from one or more of propanol, butanol, pentanol, isopropanol, isobutanol, and sec-butanol; more preferably, the monohydric alcohol is sec-butanol.

[0018] Secondly, the present invention provides a method for preparing a durable superhydrophobic nano-coating. The preparation method includes: first stirring ethylenediaminetetraacetic acid, a hydrophilic nano-silica dispersion, anhydrous ethanol, a monohydric alcohol, and a perfluoroorganosilane to obtain a mixed solution; adding a catalyst to the mixed solution, and then subjecting the mixed solution after adding the catalyst to a second stirring; after stirring, dispersing the reaction solution at high speed to obtain the durable superhydrophobic nano-coating.

[0019] Preferably, the temperature of the first stirring is 40-60°C, and the time is 10-60 minutes.

[0020] Preferably, the temperature of the second stirring is 40–70°C, and the time is 2–12 hours. Attached Figure Description

[0021] Figure 1 These are the water contact angle (left) and oil contact angle (right) of Example 1; Figure 2 These are the water contact angle (left) and oil contact angle (right) of Example 2; Figure 3 The water contact angle (left) and oil contact angle (right) are shown in Comparative Example 1. Figure 4 The water contact angle (left) and oil contact angle (right) are shown in Comparative Example 2. Figure 5 The water contact angle (left) and oil contact angle (right) are shown in Comparative Example 3. Figure 6 The water contact angle (left) and oil contact angle (right) are shown in Comparative Example 4. Figure 7 The comparison is shown in Example 5, showing the water contact angle (left) and oil contact angle (right). Figure 8 The comparison is shown in Example 6, showing the water contact angle (left) and oil contact angle (right). Figure 9 The figures show the water contact angle (left) and oil contact angle (right) of Comparative Example 7. Detailed Implementation

[0022] The present invention is further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention. The following exemplarily illustrates the durable superhydrophobic nanocoating and its preparation method according to the present invention.

[0023] The raw material composition of the durable superhydrophobic nano-coating includes: by weight, 5-50 parts of ethylenediaminetetraacetic acid, 0.1-50 parts of hydrophilic nano-silica dispersion, 10-50 parts of anhydrous ethanol, 10-50 parts of monohydric alcohol, 0.1-20 parts of perfluorinated organosilane, and 0.1-5 parts of catalyst.

[0024] Preferably, the raw material composition of the durable superhydrophobic nano-coating includes: by weight, 14-18 parts of ethylenediaminetetraacetic acid, 5-11 parts of hydrophilic nano-silica dispersion, 20-26 parts of anhydrous ethanol, 47-50 parts of monohydric alcohol, 2-6 parts of perfluorinated organosilane, and 0.1-1 parts of catalyst.

[0025] In some embodiments, the silica concentration of the hydrophilic nano-silica dispersion is 10–30 wt%. Controlling the silica concentration within this range allows the coating to simultaneously achieve good dispersibility and toughness on the substrate surface without altering the substrate's appearance. The solvent for the hydrophilic nano-silica dispersion is selected from one or more mixtures of methanol, ethanol, isopropanol, butanol, sec-butanol, isobutanol, butanone, and water. For example, in the various embodiments and comparative examples, a hydrophilic nano-silica dispersion with a silica concentration of 20 wt% (ethanol as the solvent) is specifically used.

[0026] Perfluoroorganosilanes are organic compounds whose chemical structure combines fluorine atoms with silane. Because all hydrogen atoms in the hydrocarbon groups of their molecules are replaced by fluorine atoms to form stable CF bonds, these fluorinated organosilanes are called perfluoroorganosilanes. Perfluoroorganosilanes are preferably long-chain perfluoroorganosilanes. Long-chain perfluoroorganosilanes have flexible carbon chains and carry a sufficient number of negative charges, giving them strong hydrophobic properties. Preferably, the number of fluorine atoms in the perfluoroorganosilane is ≥13.

[0027] More preferably, the perfluoroorganosilane is one or a mixture of perfluorodecyltriethoxysilane, perfluorodecyltrimethoxysilane, perfluorohexadecyltriethoxysilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctylsilane.

[0028] In some embodiments, the mass ratio of the nano-silica to the perfluoroorganosilane is between (0.1 to 4): 1, preferably between (0.3 to 2): 1, more preferably between (0.3 to 1): 1, and even more preferably between (0.3 to 0.6): 1.

[0029] In some embodiments, the mass ratio of the perfluoroorganosilane to the catalyst is between (10-100):1, preferably between (10-60):1, more preferably between (10-50):1, and even more preferably between (30-50):1.

[0030] A monohydric alcohol, also known as a primary alcohol, is an alcohol compound in which one hydroxyl group is attached to a carbon chain. In a monohydric alcohol, only one other carbon atom is attached to the carbon atom to which the hydroxyl group is attached. The monohydric alcohol is selected from one or more of propanol, butanol, pentanol, isopropanol, isobutanol, and sec-butanol. Preferably, the monohydric alcohol is sec-butanol. sec-butanol can improve the extensibility and adhesion of coatings, promote the uniform adhesion of superhydrophobic nano-coatings to the substrate, and improve the stability of modified nano-silica particles. In addition, sec-butanol partially hydrolyzes into acetic acid and butyl ester under constant temperature acidic conditions, which can reduce the viscosity of the coating and improve its fluidity and drying speed.

[0031] The catalyst accelerates the hydrolysis of perfluoroorganosilanes and promotes the grafting of the hydrolysis products onto nanoparticles. The catalyst can be one or more of the following: glacial acetic acid, hydrochloric acid, sulfuric acid, nitrous acid, phosphoric acid, formic acid, oxalic acid, propionic acid, and maleic acid.

[0032] The following exemplarily illustrates the preparation method of the durable superhydrophobic nanocoating of the present invention.

[0033] The mixture was first stirred with ethylenediaminetetraacetic acid, hydrophilic nano-silica dispersion, anhydrous ethanol, monohydric alcohol, and perfluoroorganosilane to obtain a mixed solution.

[0034] The temperature for the first stirring is 40–60°C, and the time is 10–60 minutes. The purpose of the first stirring is to ensure that the mixture is heated evenly, and to avoid uneven hydrolysis of perfluoroorganosilanes and uneven grafting of hydrolysates onto the nanoparticle surface caused by uneven heating.

[0035] Add the catalyst to the mixture after the first stirring. The catalyst can be added dropwise.

[0036] If the catalyst is added at the same time as other raw materials, the grafting rate on the nano silica particles will vary greatly, making the superhydrophobic and dihydrophobic properties unstable, or unable to exhibit excellent dihydrophobic effects.

[0037] The mixture after adding the catalyst is subjected to a second stirring. The temperature of the second stirring is 40–70°C, and the time is 2–12 hours. The purpose of the second stirring is to promote the contact between the hydrolysis products of perfluoroorganosilanes and the nano-silica particles, and to facilitate the effective grafting of the hydrolysis products of perfluoroorganosilanes and nanoparticles.

[0038] After the second stirring is completed, the reaction solution is dispersed at room temperature and high speed to obtain the durable superhydrophobic nano-coating.

[0039] In an organic solvent environment, the silicon-oxygen bonds of perfluoroorganosilanes break, and a continuous reaction is formed to form silanols. The silanols encapsulate the hydrophilic (with negatively charged hydroxyl groups on the surface) nano-silica particles suspended in the organic solvent. The silanols generated by the organosilanes undergo a condensation reaction with the hydroxyl groups on the surface of the nano-silica particles, thereby achieving the encapsulation of the hydrolyzed organosilanes on the nano-silica particles and completing the modification of the nano-silica particles.

[0040] The durable superhydrophobic and superoleophobic nanocoating is particularly suitable for fabric surfaces. The coating encapsulates and adheres to the fibers of the fabric. The organic solvents in the coating evaporate very quickly at room temperature, helping the modified nano-silica particles to embed into the fiber gaps and spread relatively evenly on the fabric surface. The nano-silica particles construct a micro-nanoscale structure on the fabric, similar to the Cassie-Baxter model, which reduces the surface energy of the substrate fibers—lower than that of water droplets or oil droplets—thus achieving a superhydrophobic and superoleophobic effect that allows oil and boiling water to roll off the fabric surface. Coating methods include, but are not limited to, spraying.

[0041] The durable superhydrophobic nano-coating of this invention achieves a water contact angle of over 160° and an oil contact angle of over 150° on the fabric surface, with both water roll-off angle and oil roll-off angle less than 2°. At room temperature, both water and oil achieve a superhydrophobic effect on the fabric surface with the durable superhydrophobic nano-coating, without trailing or leaving marks.

[0042] The durable super-hydrophobic nano-coating of the present invention, when tested according to the GB / T30159.1-2013 standard for the detection and evaluation of stain resistance of textiles, achieves a liquid stain resistance level of 5.

[0043] The durable super-dual-hydrophobic nano-coating of the present invention, when tested according to the GB / T 19977 standard for oil repellency and hydrocarbon resistance of textiles, achieves an oil repellency level of 6.

[0044] The durable superhydrophobic nano-coating of the present invention, according to the HG / T 5367.-2022 standard, has an initial icing force that can be tested to achieve easy de-icing protection.

[0045] The durable superhydrophobic and superoleophobic nano-coating of the present invention, after being sprayed onto a fabric, is tested according to method B in the standard for determining the heat resistance of fabric coatings to air aging, FZ / T 01008. After aging for 720 hours, the water and oil contact angles only decrease by 2 to 4°, and the superhydrophobic and superoleophobic properties are still maintained.

[0046] Furthermore, existing technologies for preparing durable superhydrophobic nanocoatings require complex operations involving multiple steps such as extraction, washing, and purification, with a single reaction time potentially exceeding 24 hours. The durable superhydrophobic nanocoating described in this invention has a simple and straightforward preparation process, requiring no interruption or removal during the operation; the reaction can be carried out solely within the container, enabling the production of large quantities of durable superhydrophobic nanocoatings in a single batch.

[0047] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0048] The contact angle and roll-off angle were measured using a contact angle measuring instrument (model SDC-100S, Dongguan Shengding Precision Instruments Co., Ltd.). The oil used in the test was Luhua 5S first-grade pressed peanut oil.

[0049] Example 1

[0050] The preparation method of the durable superhydrophobic nano-coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, and 4 parts by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the durable superhydrophobic nano-coating.

[0051] The durable superhydrophobic nanocoating of Example 1 was applied to the fabric surface, and the contact angle and roll-off angle were tested after drying. Figure 1 These are the water contact angle (left) and oil contact angle (right) of Example 1. It can be seen that the water contact angle of the sample in this example is 164.115°, the oil contact angle is 156.543°, the water roll-off angle is <2°, and the oil roll-off angle is <2°.

[0052] Example 2

[0053] The preparation method of the durable superhydrophobic nano-coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 11 parts by weight of hydrophilic nano-silica dispersion, 21 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, and 4 parts by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the durable superhydrophobic nano-coating.

[0054] The durable superhydrophobic nanocoating of Example 2 was applied to the fabric surface, and the contact angle and roll-off angle were tested after drying. Figure 2 These are the water contact angle (left) and oil contact angle (right) of Example 2. It can be seen that the water contact angle of the sample in this example is 162.013°, the oil contact angle is 150.468°, the water roll-off angle is <2°, and the oil roll-off angle is <2°.

[0055] Example 3

[0056] The preparation method of the durable superhydrophobic nano-coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 11 parts by weight of hydrophilic nano-silica dispersion, 21 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, and 4 parts by weight of perfluorohexadecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the durable superhydrophobic nano-coating.

[0057] Example 4

[0058] The preparation method of the durable superhydrophobic nano-coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 11 parts by weight of hydrophilic nano-silica dispersion, 21 parts by weight of anhydrous ethanol, 50 parts by weight of pentanol, and 4 parts by weight of tridecafluorooctyltrimethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the durable superhydrophobic nano-coating.

[0059] Comparative Example 1

[0060] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, and 4 parts by weight of 4-fluorotriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0061] The coating of Comparative Example 1 was applied to the fabric surface, and contact angle and roll-off angle tests were performed after drying. Figure 3 The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 1. It can be seen that the water contact angle of this comparative example sample is 46.805°, and the oil contact angle is 2.480°; neither water nor oil can roll onto the fabric. Compared to Example 1, the water and oil contact angles of the substrate surface treated in this comparative example are significantly reduced, and the fabric surface after treatment exhibits a hydrophilic and oleophilic state. Under the same preparation method, replacing the perfluorinated organosilane with a short-chain fluorinated organosilane (fluorine atom number < 13) results in a lower negative charge on the fluorine chain, even though the short fluorinated chain also has low polarizability and short CF bonds. After hydrolysis, the surface energy grafted onto nanoparticles for modification is higher, resulting in a poorer superhydrophobic effect of the coating.

[0062] Comparative Example 2

[0063] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 11 parts by weight of hydrophilic nano-silica dispersion, 21 parts by weight of anhydrous ethanol, 50 parts by weight of isopropanol, and 4 parts by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring is carried out under a 50°C water bath heating condition for 30 minutes. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring is carried out under a 50°C water bath heating condition. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0064] ① Second stirring time 4 hours: The coating of Comparative Example 2 was applied to the fabric surface and the contact angle and roll-off angle were tested after drying. Figure 4 (a) shows the water contact angle (left) and oil contact angle (right) of Comparative Example 2 after a second stirring time of 4 hours. The water contact angle of this sample is 43.603° and the oil contact angle is 7.979°, indicating that the treated substrate surface exhibits a hydrophilic and oleophilic state.

[0065] ② Second stirring time 8 hours: The coating of Comparative Example 2 was applied to the fabric surface and the contact angle and roll-off angle were tested after drying. Figure 4 (b) shows the water contact angle (left) and oil contact angle (right) of Comparative Example 2 after a second stirring time of 8 hours. The water contact angle of this sample was 142.028°, and the water roll-off angle was <2°; the oil contact angle was 102.037°, and the oil roll-off angle was 36°.

[0066] ③ Second stirring time 16 hours: The coating of Comparative Example 2 was applied to the fabric surface and the contact angle and roll-off angle were tested after drying. Figure 4 (c) Comparative Example 2, water contact angle (left) and oil contact angle (right) after a second stirring time of 16 hours. The water contact angle of this sample was 159.500°, and the water roll-off angle was <2°; the oil contact angle was 147.079°, and the oil roll-off angle was 7°.

[0067] The solvent in a coating affects the hydrolysis process of perfluoroorganosilanes. Perfluoroorganosilanes (such as perfluorodecyltriethoxysilane) have lower solubility in isopropanol than in sec-butanol. Compared to using sec-butanol as a solvent, using isopropanol reduces the grafting and encapsulation rate of the silanols produced after hydrolysis of perfluoroorganosilanes onto the nanoparticle surface. Therefore, when the reaction time is short, the water contact angle and oil contact angle of the coating cannot achieve the desired hydrophobic and oleophobic effect. However, as the reaction time increases, the superhydrophobic and superoleophobic properties of the coated fabric surface become more pronounced.

[0068] Comparative Example 3

[0069] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, 4 parts by weight of perfluorodecyltriethoxysilane, and 0.1 parts by weight of glacial acetic acid are stirred, and then discharged to obtain the reaction mixture. The stirring conditions are 50°C water bath heating for 4 hours. The reaction mixture is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0070] The coating of Comparative Example 3 was applied to the fabric surface, and contact angle and roll-off angle tests were performed after drying. Figure 5The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 3. The water contact angle of this comparative sample is 42.771°, and the oil contact angle is 3.887°. It can be seen that compared to Example 1, both the water and oil contact angles of this comparative example are significantly reduced, indicating that the fabric surface treated in this comparative example exhibits a hydrophilic and oleophilic state. Directly adding the catalyst glacial acetic acid resulted in incomplete hydrolysis of the perfluoroorganosilane, leading to a large number of active groups on the nanoparticle surface bonding with water, thus preventing the coating from exhibiting amphiphilic properties. Therefore, a step of moderately stirring the mixture before adding the catalyst glacial acetic acid is preferable to improve the superamphiphilic properties of the coating.

[0071] Comparative Example 4

[0072] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 50 parts by weight of sec-butanol, 4 parts by weight of perfluorodecyltriethoxysilane, and 0.1 parts by weight of ammonia water are stirred, and then the mixture is discharged to obtain the reaction material. The stirring conditions are: stirring at 50°C in a water bath for 4 hours. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0073] The coating of Comparative Example 4 was applied to the fabric surface, and contact angle and roll-off angle tests were performed after drying. Figure 6 The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 4. It can be seen that the water contact angle of this comparative example sample is 42.242°, and the oil contact angle is 48.651°, meaning neither water nor oil can roll onto the fabric. Compared to Example 1, the water and oil contact angles of this comparative example are significantly reduced, indicating that the treated substrate surface exhibits both hydrophilic and oleophilic properties. Under acidic conditions, the electron cloud density of silicon atoms on fluorinated organosiloxanes decreases, making it easier for hydroxyl groups attached to silicon atoms to condense with the hydroxyl groups on the surface of nano-silica particles. Under alkaline conditions, on the one hand, there are more types of catalytic reactions, making it difficult for the groups grafted onto the nanoparticle surface to remain consistent; on the other hand, fluorinated anionic particles easily lose silicon groups under alkaline conditions. Furthermore, during the operation of this comparative example, the presence of ammonia in the sample resulted in a strong irritating odor during application, which could easily cause discomfort to the operators.

[0074] Comparative Example 5

[0075] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 46 parts by weight of sec-butanol, and 8 parts by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0076] The coating of Comparative Example 5 was applied to the fabric surface, and contact angle and roll-off angle tests were performed after drying. Figure 7 The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 5. It can be seen that the water contact angle of this comparative sample is 137.789°, and the water roll-off angle is 8°; the oil contact angle is 104.427°, and the oil roll-off angle is 23°. Compared to Example 1, the water and oil contact angles of this comparative example are slightly lower, and it does not exhibit superhydrophobicity. The hydrolysis of perfluoroorganosilanes requires contact with glacial acetic acid. If the mass ratio of perfluoroorganosilane to catalyst is too high, the opportunity for perfluoroorganosilane to contact with glacial acetic acid is reduced, resulting in insufficient active sites for contact. Ultimately, the hydrolysis rate of the perfluoroorganosilane decreases, manifested as a decrease in the water and oil contact angles.

[0077] Comparative Example 6

[0078] The preparation method of the coating includes the following steps: 14 parts by weight of ethylenediaminetetraacetic acid, 6 parts by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 46 parts by weight of sec-butanol, and 1 part by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring is performed under a water bath heating condition of 50°C for 30 minutes. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring is performed under a water bath heating condition of 50°C for 4 hours. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0079] The coating of Comparative Example 6 was applied to the fabric surface, and the contact angle and roll-off angle were tested after drying. Figure 8The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 6. It can be seen that the water contact angle of this comparative sample is 99.683°, the water roll-off angle is 5°, and the oil contact angle is 43.518°. Compared to Example 1, both the water and oil contact angles of this comparative example are significantly reduced, indicating that the treated fabric surface still cannot achieve superhydrophobicity. Perfluoroorganosilanes undergo complete hydrolysis under the action of a catalyst to form silanols. If the mass ratio of hydrophilic nano-silica to perfluoroorganosilane is too high, the number of silanols grafted onto the nanoparticle surface is not dense enough, and the surface energy of the nanoparticles cannot achieve oleophobicity or even exhibits an oleophilic state.

[0080] Comparative Example 7

[0081] The preparation method of the coating includes the following steps: 18 parts by weight of ethylenediaminetetraacetic acid, 1 part by weight of hydrophilic nano-silica dispersion, 26 parts by weight of anhydrous ethanol, 51 parts by weight of sec-butanol, and 4 parts by weight of perfluorodecyltriethoxysilane are subjected to a first stirring to obtain a mixture. The first stirring condition is stirring for 30 minutes under a water bath heating condition at 50°C. 0.1 parts by weight of glacial acetic acid are added to the mixture, followed by a second stirring, and then the mixture is discharged to obtain the reaction material. The second stirring condition is stirring for 4 hours under a water bath heating condition at 50°C. The reaction material is then dispersed at room temperature using high-speed cutting to obtain the coating.

[0082] The coating of Comparative Example 7 was applied to the fabric surface, and the contact angle and roll-off angle were tested after drying. Figure 9 The images show the water contact angle (left) and oil contact angle (right) of Comparative Example 7. It can be seen that the water contact angle of this comparative example sample is 50.461°, and the oil contact angle is 9.659°. Compared to Example 1, both the water and oil contact angles of this comparative example are significantly reduced, indicating that the treated fabric surface exhibits a hydrophilic and oleophilic state. Perfluoroorganosilanes can be catalyzed to complete hydrolysis by glacial acetic acid, and the surface of nanoparticles can be completely grafted with silanols. However, due to the low mass ratio of nano-silica to perfluoroorganosilane, the actual number of nanoparticles is too small. When treated on a substrate by spraying, the nanoparticles cannot form a continuous and effective rough, low surface energy superhydrophobic coating.

[0083] The anti-fouling test was conducted according to GB / T 3015.9.

[0084] Oil resistance test according to GB / T 19977.

[0085] Anti-icing tests were conducted according to HG / T 5367.-2022, the testing specifications for ice resistance. A super-hydrophobic coating was applied to the test plate. A stainless steel ring of the required dimensions was placed horizontally on the test plate and secured with rubber bands. The test plate and ring were placed in a -20°C freezer for 21 hours to freeze the water. After removing the rubber bands, the plate was frozen again at -20°C for 3 hours. The ring and plate were then transferred to a -10°C environment and kept there for 5 minutes. Before testing, the test plate was fixed to the lower clamp of the tensile testing machine, and the hole of the stainless steel ring was connected to the upper clamp of the machine with a steel wire rope. The tensile speed was maintained at 30 mm / min. A digital display tensile testing machine was used to determine the minimum force required for the steel ring and any ice within it to detach from the test plate, expressed in Newtons (N).

[0086] Durability testing was conducted according to Method B of FZ / T 01008. Samples were baked in a ventilated oven at 70±1℃ under normal pressure, ensuring the samples were not under tension and both sides were exposed to hot air. Only samples treated in the same manner were placed in the oven during the test. The durability test ended when the water / oil contact angle decreased by 5°. Water / oil contact angle tests were performed on the samples every 24 hours. When the test duration reached 720 hours, if the decrease in water / oil contact angle of the aged sample compared to before aging was less than 5°, the test was also terminated, and the durability duration was recorded as 720 hours.

[0087] The performance test results of the superhydrophobic coatings prepared in each embodiment and comparative example are shown in the table below.

[0088] Table 1

[0089] The durable superhydrophobic nano-coating of this invention achieves a water contact angle of over 160° and an oil contact angle of over 150° on the fabric surface, with both water roll-off angle and oil roll-off angle less than 2°. At room temperature, both water and oil achieve a superhydrophobic effect on the fabric surface where the durable superhydrophobic nano-coating is formed, without trailing or leaving marks.

[0090] The durable super-hydrophobic nano-coating of the present invention, when tested according to the GB / T30159.1-2013 standard for the detection and evaluation of stain resistance of textiles, achieves a liquid stain resistance level of 5.

[0091] The durable super-dual-hydrophobic nano-coating of the present invention, when tested according to the GB / T 19977 standard for oil repellency and hydrocarbon resistance of textiles, achieves an oil repellency level of 6 or above.

[0092] The durable superhydrophobic nano-coating of the present invention, according to the HG / T5367.5 standard, has an initial icing force that can be tested to achieve easy de-icing protection.

[0093] The durable superhydrophobic and superoleophobic nano-coating of the present invention, after being sprayed onto a fabric, is tested according to Method B in the standard for determining the heat resistance of fabric coatings to air aging, FZ / T 01008. After aging for 720 hours, the water and oil contact angles decrease by only 2 to 4 degrees compared to before aging, and the superhydrophobic and superoleophobic properties are still maintained.

Claims

1. A durable superhydrophobic nano-coating, characterized in that, The raw material composition of the durable superhydrophobic nano-coating includes: by weight, 5-50 parts of ethylenediaminetetraacetic acid, 0.1-50 parts of hydrophilic nano-silica dispersion, 10-50 parts of anhydrous ethanol, 10-50 parts of monohydric alcohol, 0.1-20 parts of perfluorinated organosilane, and 0.1-5 parts of catalyst.

2. The durable superhydrophobic nanocoating according to claim 1, characterized in that, The raw material composition of the durable superhydrophobic nano-coating includes, by weight, 14-18 parts of ethylenediaminetetraacetic acid, 5-11 parts of hydrophilic nano-silica dispersion, 20-26 parts of anhydrous ethanol, 47-50 parts of monohydric alcohol, 2-6 parts of perfluorinated organosilane, and 0.1-1 parts of catalyst.

3. The durable superhydrophobic nanocoating according to claim 1 or 2, characterized in that, The perfluoroorganosilane is a long-chain perfluoroorganosilane; preferably, the long-chain perfluoroorganosilane has ≥13 fluorine atoms; more preferably, the perfluoroorganosilane is selected from one or more of perfluorodecyltriethoxysilane, perfluorodecyltrimethoxysilane, perfluorohexadecyltriethoxysilane, tridecafluorooctyltriethoxysilane, tridecafluorooctyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctylsilane.

4. The durable superhydrophobic nanocoating according to any one of claims 1 to 3, characterized in that, The silica concentration of the hydrophilic nano silica dispersion is 10-30 wt%; preferably, the solvent of the hydrophilic nano silica dispersion is selected from one or more mixtures of methanol, ethanol, isopropanol, butanol, sec-butanol, isobutanol, methyl ethyl ketone, and water.

5. The durable superhydrophobic nanocoating according to any one of claims 1 to 4, characterized in that, The mass ratio of the nano-silica to the perfluorinated organosilicon is between (0.1-4):1, preferably between (0.3-2):1, and more preferably between (0.3-1):

1.

6. The durable superhydrophobic nanocoating according to any one of claims 1 to 5, characterized in that, The catalyst is selected from one or more of the following: glacial acetic acid, hydrochloric acid, sulfuric acid, nitrous acid, phosphoric acid, formic acid, oxalic acid, propionic acid, and maleic acid.

7. The durable superhydrophobic nanocoating according to any one of claims 1 to 6, characterized in that, The monohydric alcohol is selected from one or more of propanol, butanol, pentanol, isopropanol, isobutanol, and sec-butanol; preferably, the monohydric alcohol is sec-butanol.

8. A method for preparing a durable superhydrophobic nanocoating according to any one of claims 1 to 7, characterized in that, The preparation method includes: first stirring ethylenediaminetetraacetic acid, hydrophilic nano silica dispersion, anhydrous ethanol, monohydric alcohol, and perfluoroorganosilane to obtain a mixture; adding a catalyst to the mixture, and then stirring the mixture after adding the catalyst; after stirring, dispersing the reaction solution at high speed to obtain the durable superhydrophobic nano coating.

9. The preparation method according to claim 8, characterized in that, The temperature of the first stirring is 40-60℃, and the time is 10-60 minutes.

10. The preparation method according to claim 8 or 9, characterized in that, The temperature of the second stirring is 40–70°C. The duration is 2 to 12 hours.

Images